If he can show the receipts for the rebuild and flow #'s for the port work then it might be worth it.
Ported/polished could mean nothing without flow #'s or proof that the work was done by a person that is reputable.
Full PG/G60 long blocks are pretty plentiful and I see them anywhere from $100-300 in used working condition.
I have a 0 mile rebuilt PG/G60 long block I'd sell for a really good price. If your interested PM me for more details.